An inotropic thyroid hormone analogue of L-thyroxine; binds to TRα and TRβ (Kas = 2.4 and 4.06 x 107 M-1, respectively, for human recombinant receptors); increases mRNA expression of α-MHC in primary rat cardiomyocytes (EC50 = ~0.5 μM); prevents myocardial infarction-induced loss of contractility ex vivo in rabbit cardiomyocytes (3.75 mg/kg per day); increases expression of VEGF, bFGF, angiopoietin-1, and Tie-2 as well as angiogenesis in non-infarcted cardiac tissue in rats (3.75 mg/kg per day); decreases infarct size expansion, stimulates arteriolar growth, and inhibits ventricular remodeling post-myocardial infarction in rats (3.5 mg/kg per day)